Nippon Moli Energy Corp.

Yuasa Corporation

Tadashi Okutoh

Shigeru Sano

Aya Nishino

Katuo Ehara

A small protector is provided for a high energy density battery such as a lithium ion battery. A flat sheet form of leading portion extending from a positive temperature coefficient element is provided thereon with at least one battery protecting circuit element for detecting at least one abnormality selected from overcharging, over-discharging, overcurrent, and unusual temperature to cut off a current passing therethrough. A fail-safe mechanism is achieved for the actuation of the positive temperature coefficient element and the actuation of the battery protecting circuit element.

Battery protector having a positive temperature coefficient element

The invention provides a protective device for batteries having a high energy density such as lithium ion batteries. The protective device comprises a battery voltage-monitoring means, an overcharge-detecting means for sending out a charge-finishing signal when a voltage detected by the battery voltage-detecting means is higher than a preset value, a charge-finishing means for finishing charge in response to the charge-finishing signal, an output-counting means for counting the number of charge-finishing signals sent out of the charge-finishing means, and a cutoff means for cutting off conduction of a current in said batteries when a counted value reaches a preset value, thereby limiting the number of permissible overcharging cycles.

Protective device for secondary batteries

An overcharge preventing device for a high energy density battery such as a lithium ion battery comprises a voltage sensor means for sensing a voltage of a battery that is being charged, a current feeder means for feeding a current to a heat generating means when a voltage sensed by said voltage sensor means exceeds a preset voltage, and a repeatedly usable thermal actuator means that is thermally coupled to said heat generation means incorporated in a charging current circuit. Upon overcharging of the battery, the thermal actuator means is actuated by heat generated from the heat generating means to interrupt feeding of a charging current to the battery. Upon elimination of an overcharged state, the charging current circuit in the thermal actuator means is resumed to recharge the battery.

Overcharge preventing device

The invention provides a protective device for batteries having a high energy density such as lithium ion batteries. The protective device includes a current conduction cutoff means having a current-conducting circuit comprising a voltage-detecting means for detecting the voltage of at least one battery being charged, a heat-generating resistance for starting the conduction of a current when the detected voltage exceeds a preset voltage, and a temperature fuse thermally coupled to the heat-generating resistance. When a state where battery voltage is higher than a preset value continues, a charging circuit for the battery is cut off by the temperature fuse and current output from the battery is disabled. The protective device further includes a battery-discharging means actuated upon detection of the fusing-down of the temperature fuse, so that the battery is disabled, and then placed in a dischargeable state.

A life indicator is so designed that an electric current flows to a light emitting diode utilizing a battery as a power source when two electrodes are electrically connected. The two electrodes are so installed as to be electrically connected by passing water through a water passage communicating with an objective equipment, and the discharge life of the battery is set equal to the service life of the equipment.

Growing community of inventors

Kawasaki, Japan

Tadashi Okutoh